If the European Commission were to levy a 12.5 percent tax on all of Apple's earnings that run through Ireland, it would reduce the company's annual earnings by just under 10 percent, a new "worst-case scenario" analysis has found.

In a research note issued to investors on Thursday, J.P. Morgan analyst Rod Hall did the math on the impact revisions to Ireland's tax code might have on Apple. A copy of the note was provided to AppleInsider.

In it, Hall noted that he remains bullish on AAPL stock, with an "overweight" rating and a price target of $145. Still, he admitted that an ongoing probe of Irish tax laws could have a noteworthy affect on the company's bottom line.

In his potential "worst-case scenario," Hall sees Apple assuming a full Irish tax rate of 12.5 percent against what he calculates as $153 billion of relevant profits over 10 years. That would total some $19 billion against the iPhone maker.

"We see even this as largely irrelevant for Apple's share price given the company's large cash pile," he said.

Looking forward, however, the impact could be greater: Hall estimates that some 59 percent, or $42 billion, of Apple's earnings before taxes run through the Irish tax structure with almost no taxes imposed on them.

If the European Commission were to levy a worst-case 12.5 percent rate on those dollars, Hall estimates that it would reduce Apple's annual earnings by just under 10 percent.

Apple itself issued a warning to investors last month, noting that the European Commission's scrutiny of Ireland's tax laws could have a "material" impact on Apple's bottom line.

Ireland, along with Luxembourg and the Netherlands, have offered sweetheart tax arrangements to large companies in exchange for setting up operations there.

A preliminary report issued by the commission last year found that Ireland's 1991 and 2007 tax records with Apple represented illegal state aid, designed to skirt market forces. Apple is thought to have saved as much as $9 billion per year from these agreements, which could be retroactively charged to the company in back taxes.

Ireland has vowed to fight any EU ruling against its tax policies, and Apple has repeatedly defended its arrangement.